Wireless infrastructure has been rapidly taking over as the cornerstone of modern communication means in the past two decades. One can now recognize the importance of GPS systems, WLAN and most importantly cellular systems (GSM/UMTS/LTE). Modern 3G and 4G systems require broad bandwidth channels of up to 20 MHz and allow high data rates of up to 100 Mb/s range utilizing non-constant envelope modulation schemes. These schemes are characterized by their high spectral efficiency and crest factor. Due to the implied demands on linearity, the power amplifier (PA) associated with the system is often operated at several dB below its peak output power with stringent requirements on both performance and price.
Financially, RF-CMOS technology provides the best option for wide-scale cheap production compared to GaAs and GaN. However, performance-wise, RF-CMOS suffers from drawbacks. Among the drawbacks is its low voltage-robustness, leading to lower achievable saturated output power. Moreover, it suffers from low efficiency and low maximum linear output power compared to the other technologies. These limitations hinder the combination of the CMOS PA with other software-defined radio blocks on a single chip to achieve true integration.